COINAPO

COINAPO is abbreviation of the full name of the COST Action MP0902: “COmposites of Inorganic NAnotubes and POlymers. COST Actions are funded by European Union within the . The Action was initiated in 2008, kicked-off in 2009 and currently comprises about 50 research groups from 26 countries. It is coordinated by prof. Irena Drevensek Olenik from University of Ljubljana in Slovenia acting as a chair, and Dr. Hans Sawade from Leibniz institute for plasma research and technology from Greifswald in Germany acting as a co-chair. All decision making procedures take place via the management committee (MC) of the action, which is at the moment composed of 42 MC members.
The main aim of the COINAPO is to generate fundamental knowledge in the field of inorganic nanotube - polymer composites and to create widespread links needed for application and commercialization of this kind of composites by European industry. This is attained by linking the groups with knowledge and expertise on synthesis and characterization of inorganic nanotube materials with groups that have experience in fabrication of polymer composites and their characterization. The best-obtained results are then promoted to suitable industrial partners.
Recent facts about inorganic nanotubes and their composites
An inorganic nanotube is a cylindrical molecule often composed of metal oxides and metal chalcogenides, which is morphologically similar to a carbon nanotube. Inorganic nanotubes are observed in some mineral deposits of natural origin. Synthetic structures of this type were first reported by the group of Reshef Tenne in 1992. Recently large amounts of WS2 and pure phase of SnS2/SnS nanotubes were successfully synthesized. Inorganic nanotubes are an interesting alternative to carbon nanotubes, showing advantages such as e.g. easy synthetic access and high crystallinity, good uniformity and dispersion, predefined electrical conductivity depending on the composition of the starting material and needle-like morphology, good adhesion to a number of polymers and high impact resistance. They are therefore promising candidates as fillers for polymer composites with enhanced thermal, mechanical, and electrical properties. Target applications for this kind of composites are materials for heat management, electrostatic dissipaters, wear protection materials, photovoltaic elements, etc. Typical nanotube-forming materials are 2D layered materials such as WS2, MoS2, etc. Another very interesting type of nanotube and nanowire forming materials are transition metal/chalcogen/halogenides (TMCH), described by the formula TM6CyHz, where TM is transition metal (molybdenum, tungsten, tantalum, niobium), C is chalcogen (sulfur, selenium, tellurium), H is halogen (iodine), and the composition is given by 8.2<(y+z)<10. TMCH tubes can have a subnanometer-diameter, lengths tunable from hundreds of nanometers to tens of microns and show excellent dispersiveness due to extremely weak mechanical inter-tube coupling. Other broadly investigated types of inorganic nanotubes are also titanium dioxide (TiO2), zinc oxide (ZnO), etc. The first attempts of making polymer composites with the TMCH nanotubes have revealed an order of magnitude improvement of the mechanical strength of cellulose fibers by adding only 0.1 wt% of the TMCH additive, while measurements of electrical conductivity of polycaprolactone doped with TMCH nanotubes revealed a percolative behavior with an extremely low percolation threshold. The addition of WS2 nanotubes to epoxy resin resulted in improved adhesion, fracture toughness and strain energy release rate. The wear of the nanotubes-reinforced epoxy was eight-times lower than that of pure epoxy. Tungsten disulfide inorganic nanotubes (WS2) were embedded into a poly-methyl-methacrylate (PMMA) nanofiber matrix via electrospinning. The nanotubes were well dispersed and aligned along fiber axis, the enhanced stiffness and toughness of PMMA fiber meshes by means of inorganic nanotubes addition may have potential applications as transparent high energy absorption materials. Optical properties of semiconductor quantum dot-inorganic nanotube hybrids reveal efficient resonant energy transfer from the quantum dot to the inorganic nanotubes upon photoexcitation. Nanodevices based on one-dimensional nanomaterials have great potential in next generation electronic and photoelectronic systems with obvious advantages in miniaturized size, faster transport speed, higher efficiency and less energy consumption. The first high-speed photodetector for visible and near-infrared lights based on individual WS2 nanotubes was prepared, and the excellent electric and optoelectronic properties of WS2 nanotubes were observed. Doped nanotubes will allow control over electrical properties of the nanodevices. First inorganic nanotube hybrids were made by filling WS2 nanotubes with molten lead iodide salt by a capillary wetting process, resulting in PbI2 in WS2 core-shell nanotubes.
Some important achievements of the COINAPO project
Several important advance steps in fabrication of nanotube materials were realized:, (a) successful functionalization of MoSI nanotubes with mercury ions in common organic solvents is now providing conductive nanowire networks; (b) successful exfoliation of MoS2 and WS2 bulk materials, down to mono-atomic sheets, opens new perspectives for fabrication of composite materials; (c) high nanotube yield achieved in common organic solvents provides materials in macroscopic quantities available to network partners; (d) functionalization of MoSI nanotubes with phthalocyanines to modify optical properties was successfully achieved and will be exploited to fabricate new composite materials.
One of the partner groups successfully developed large-scale synthesis of WS2 nanotubes, which are easily dispersible in various polymers and are now available for incorporation in composites. This will lead to numerous further studies and eventually to many applications.
The bonding mechanism of MoSI nanotubes with gold nanoparticles was elaborated. This opens up new pathways towards sophisticated data processing systems that can be incorporated into various polymer materials.
Practically first ever made composite materials of MoSI and MoS2 nanotubes with polymers and elastomers were fabricated as a result of networking through the Action. First characterization experiments on these composite materials were also performed (electrical conductivity, optical spectroscopy, elastomechanic properties, adhesive properties, etc.).
Optimization of hydrothermal synthesis of TiO2 nanotubes was performed. The main parameters of the synthesis are temperature, time and gel composition. After characterization by XRD, FTIR, SEM and TEM, the best synthesis parameters were chosen. These nanotubes can no be provided to network partners for further investigations.
Demonstration was made that incorporation of inorganic nanowires of MoSI-, MoS2-, MoO3-x- type into thermoplastic engineering polymers (such as polyamide 6) reduces the coefficient of friction by about 30% and reduces the wear rate by about 50%. Currently composites based on PET are under investigation showing very similar effects.
Demonstration of alignment of inorganic nanotubes in commercial block-copolymers was performed. Alignment in a flow field occurs when the morphology of the matrix is cylindrical, but not when the matrix has a phase morphology of dispersed spheres. This observation demonstrates the importance of the anisotropy of the matrix in order to achieve alignment of nanowires / nanotubes in a polymeric matrix in a flow field.
Chips for frequency filtering were prototyped in a 130 nm radio frequency CMOS technology. The system included analog control signals for frequency and bandwidth tuning. The chips have passed tests and are appropriate for the signal reading from semiconducting and dielectric nanomaterials. The next step will be the integration of nanotubes on the designed microelectronic chip for the examination as a possible electronic element or sensor.
The effective and convenient tools for nondestructive characterization of nanocomposite material properties needed to define performance, reliability and safety requirements for composite products have been developed and validated. Such devices are prerequisite for transfer of the inorganic nanotube - polymer composite materials from research laboratories to the industrial production.
List of COINAPO meetings
*1st Management Committee meeting, Brussels, Belgium, 6 November 2009
*1st Working Group meeting, Greifswald, Germany, 8-9 March 2010
*2nd Management Committee meeting , Greifswald, Germany, 10 March 2010
*2nd Topical meeting, Zaragoza, Spain, 25-26 October 2010
*3rd Topical meeting, Sestriere, Italy, 2-3 March 2011
*3rd Management Committee meeting, Sestriere, Italy, 4 March 2011
*1st Summer School on Materials Characterization, Oxford, United Kingdom, 25-27 July

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